Definitely friendships can ebb and flow a little.
But you say she gave you daily support, when you were in a bad place, and now you will "find time for her if she needs it".
It reads to me as if she's gone from being a very, very close supportive friend to you, to someone you will keep up casually.
You have an amazing boyfriend and new social life, and she can't be a part of it apparently? You can't include her in nights out.
Whenever I had boyfriends and friends didn't, we always included each other socially in our weekend plans.
It's called looking out for each other. We never left any "soldier" behind!
Your absolute refusal to take on board even the slightest possibility that your friend feels dropped and let down, is telling.
Nice people don't do that to friends.
Instead of being so defensive, how about taking time to think about where your friend, who supported you, is at.
She can feel both happy for you but hurt to be so comprehensively sidelined.
She supported you when you were in an awful place. She sounds hurt and a bit low now.....where are you?